1. Field of the Invention
This invention relates to computer systems and, more particularly, to three dimensional packaging arrangements for providing very high density computer systems and other hybrid circuit systems.
2. History of the Prior Art
The development of computers has progressed along two avenues. First, there has been the constant search for higher speeds and more capability. In general, this has required more and larger circuit arrangements using faster components. At the same time, there has been the desire to place more and more powerful computers within the reach of individuals. Thus, there is a constant attempt to make desktop computers more powerful and at the same time smaller. To some extent, these twin desires have aided one another while in other ways they have been opposed. For example, the search for faster speeds of operation and higher packing densities to give more power to a computer has tended to reduce the size of components and the length of the conductors connecting those components. On the other hand, the staggering numbers of connectors necessary to modern computer circuits has to a great degree placed an ultimate limit on how small they can be made.
In general, typical personal computers and work stations today are constructed with their major components such as central processors, cache memory, input/output circuitry, and some random access memory laid out on a primary circuit board called a motherboard. Individual components such as additional processors, more random access memory, and hard disk controllers are all adapted to fit into connectors along an open air bus on the motherboard. This arrangement allows components to be cooled by air driven by fans and circulated through the circuit boards. It also allows individual circuit boards to be removed from and placed into the computer in the field by the user. However, the size reduction possible with such an arrangement is quite limited, especially if the addition in the field of a substantial number of peripheral components is to be allowed.